Intel XENIX 286 Programmers Guide (86) - Tenox.tc

XENIX Programming Programming Commands
m4 (continued)
Macro Calls
Macro calls have the form
name(arg 1 ,arg2, ... , argn)
The ( must immediately follow the name of the macro. If a defined macro name is not
followed by a (, it is deemed to have no arguments. Leading unquoted blanks, tabs, and
newlines are ignored while collecting arguments. When the first character is not a
digit, the macro name could consist of a letter, digit, or underscore (_) .
Left and right single quotation marks are used to quote strings. The value of a quoted
string is the string stripped of the quotation marks.
When a macro name is recognized, its argu ments are collected by searching for a
matching right parenthesis. Macro evaluation proceeds normally during the collection
of the arguments, and any com mas or right parentheses that happen to turn up within
the value of a nested call are as effective as those in the original input text. After
argument collection, the value of the macro is pushed back onto the input stream and
rescanned.
m4 makes available the following built-in macros. They may be redefined, but once this
is done the original meaning is lost. Their values are null unless otherwise stated.
define
The second argument is installed as the value of the macro whose name is the
first argument. Each occurrence of $n in the replacement of text, where n is a
digit, is replaced by the n-th argument. Argument 0 is the name of the macro;
missing arguments are replaced by the null string; $# is replaced by the number
of arguments; $* is replaced by a list of all the arguments separated by commas;
$@. is like $*, but each argu ment is quoted (with the current quotation marks).
undefine
Removes the definition of the macro named in its argu ment.
defn
pushdef
Like define, but saves any previous definition.
popdef
ifdef
Returns the quoted definition of its argument(s). It is useful for renaming
macros, especially built-ins.
Removes current definition of its argu ment(s), exposing the previous ones if any.
If the first argument is defined, the value is the second argument, otherwise the
third. If there is no third argument, the value is null. The word XENIX is
predefined in m4.
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